Throttle lock mechanism



April 8,"1958 A, w. MALL ET AL THROTTLE LOCK MECHANISM Filed Jan. 31,1955 United States Patent THROTTLE LOCK MECHANISM Arthur W. Mall,Flossmoor, Robert G. Sholeen, Chicago Heights, and Peter Walzak,Chicago, Ill., assignors to Mall Tool Company, Chicago, Ill., acorporation of Illinois Application `laiulary 31, 1955, Serial No.485,242

7 Claims. (Cl. 74-532) This invention relates to an improved handlestructure for an internal combustion engine and more particularly isdirected to a throttle lock installed in the handle of a portablegasoline engine.

Described in copending application, Serial No. 485,243, Arthur W. Mall,Charles A. Mattson and Walter Ziegler, is an engine so provided that thetransmission of a pump, generator, or chain saw attachment, forillustration, clamped on the engine housing is automatically connectedto be driven by the engine. This engine has a manually operatedthrottle, a lock which may be set to hold the throttle wide open, and agovernor to automatically control engine speed.

It is a principal object of the present invention to provide a throttlelock which may be used on an internal combustion engine of the typedescribed in said copending application. Locking the throttle lon thisengine enables the governor to automatically control engine speed, themanually operated throttle trigger being rendered temporarilyinoperative.

A. further object is to provide a throttle lock mechanism which iseasily manipulated and so arranged that only 'by following a prescribedsequence of operations may the mechanism be set. Thus the invention ischaracterized by a safety feature in such a mechanism, namely that thelock cannot be set when the engine is running at high speed but firstthe throttle must be closed and the engine idling.

lt is another object to provide a mechanism simple and economical tomanufacture having few parts and easily installed on an engine.

Other and additional objects will become apparent from a. reading of thefollowing description taken in connection with the accompanyingdrawings, wherein:

Fig. l is a View in side elevation of the handle of an internalcombustion engine, equipped with the throttle lock mechanism;

Fig. 2 is a view in side elevation of the right hand half of the handleshown in Fig. 1 (with the left hand half removed), land the partscomprising the throttle lock mechanism shown in place;

Fig. 3 is a view in section taken on lines 3-3 of Fig. 2 through thelock button;

Fig. 4 is a view in side elevation similar to the view of the right handhalf of the handle shown in Fig. 2, but with the trigger shown raised inthe handle.

Referring to Fig. l, a portable gasoline engine has a pistol grip handle11 having a trigger 12 which through a linkage 13 adjusts the throttlevalve in the carburetor of the engine. Engineltl may have a shroud 14(Fig. l) provided With a gas tank cap 15 which permits access to the gastank lying under the shroud. Shown for illustrative purposes only, theengine may be provided with a ground switch 16 for convenience fastenedon the top and in the front of the handle 11.

It will be understood that by squeezing the trigger 12 the link 13 israised to 'adjust the throttle valve in the carburetor. In the positionshown in Fig. 1 the trigger is '2,829,537 Patented Apr. s, `195strailing portion resting against the edge of the opening 18 in theforward part of the grip portion 19 of the handle through which theenlarged front part 20 of the trigger extends into the open area of thehandle. Throttle trigger 12 comprises a piece of sheet metal orthe likestamped into a U or channel form (Fig. 3) and is pivoted on a pin 21which in the structure shown is a screw to hold together the left-hand22 and right-hand 23 parts of the handle 11.

Hooked around this same pin 21 is a tension spring 24 which extendsforward within the grip portion of the handle and is secured to athrottle lock button 25 which slides in the top of the handle. A portionof each of the two halves of the handle is cut away to provide asubstantially rectangular slot 26 having edges gripping the button 25.The sides of the button are formed with grooves 27 and 28 (Fig. 3)engaged by the edges of the slot yin the handle and thus the button mayslide back and forth within the slot between the forward 29 and back 30edge which function as stops limiting the movement thereof.

Button 25 may be a casting or the like of metal or plastic material andincludes a rounded head 31 which projects above the top of the gripportion of the handle and also has a knurled portion to aid inmanipulating the button. A depending portion 32 extends a substantialdistance into the cavity of the handle and is provided at its lower endwith a hook formed by the recess or notch 33 which is adapted to engagethe throttle trigger 12 and hold the trigger in a raised positioncorresponding `to wide open throttle. As shown in Figs.. 2 and 3 thechannel shaped trigger 12 has a cross pin 34 fastened as by swaging theends to the sides of the trigger. In the raised position of the triggershown in Fig. 2 the cross pin is engageable by the hook portion 33 ofthe lock button so as yto secure and retain the trigger in the raisedposition.

In Fig. 2 the assembly is shown with the left hand half of the handleremoved and with the parts shown as they appear when th-e throttletrigger is locked by the button in its raised position. lt maybeobserved that this right hand half 23 of the handle may be formed ofmetal or plastic material vby die casting or by the use of similarmethods of forming parts, and comprises thegrip portion 19 and theforward portion 35 which provides a cavity to receive the mechanism (notshown) of the grounding switch 16.

As shown in Fig. l the button 25` is held against the back edge of theslot by virtue of the spring 24. When in this position the button willnot touch or interfere with the cross pin of trigger 12 as the pin israised to a position in front of the depending portion of the buttonfor, as may be observed from Fig. 4, the cross pin will pass entirely bythis portion of the button and will not contact or engage the buttonunless the button is pushed forward when the trigger is in the raisedposition. Thus during normal operation of the engine, .as depicted inFig. 4, which shows the button 25 pushed away from the back of the slot,the depending portion will engage or abut against the cross pin 34 toprevent further movement if attempt is made to urge the button forwardwhen the trigger is in the raised position corresponding to wide openthrottle.

In operating an engine with this handle assembly and throttle lockmechanism, the trigger may be manually` actuated to regulate the enginespeed and will notfbe interfered with when the button is in theinoperative position.

Further, to engage the trigger itis necessary the operator` follow aprescribed sequence of operations' since it is;

lfirst necessary to lower the trigger suiciently to allow the button tobe pushed forward toward the front edge of the slot in the top of thegrip portion of the handle. After the button has been pushed to theforward position (shown in dotted lines in Fig. 2) the throttle triggermay be squeezed to elevate the cross pin to a position where it may beengaged by the hook under the button, as the button slides back in theslot. The button is located on the Ioutside of the handle so that whenthe handle is gripped in a conventional manner, it may be manipulatedwith the thumb and easily urged back and forth in the slot.

By forming the trigger 12 channel in section (Fig. 3) the dependingportion 32 of the button is conned between the sides of the triggerproviding a structure where the button is restrained laterally both inthe area of the slot and at the lower portion. This feature, along withthe provision of grooves 4in the sides of the button which allows thebutton to slide in the slot prevents jamming resulting from canting ofthe button in either the forward or lateral direction.

A handle assembly equipped with -a trigger and mechanisrn for lockingthe trigger in a position corresponding to wide open throttle may beused on an engine adapted to operate different machine attachments andprovided with a governor to control engine speed. When this engine isinstalled on a generator which might be used for providing emergencyelectrical power, the governor is rst set to regulate the engine speedin accordance with the rated speed of the generator. The throttletrigger is then rendered inoperative through the use of the throttlelock mechanism disclosed herein, and the governor controlvsubstituted toautomatically regulate engine speed.

If this engine is installed on a power saw transmission, the governor isset to establish a limit on the no-load speed of the engine, to preventthe engine being operated at excessive speeds. The throttle lockmechanism, however, is not employed for safety reasons and the throttleis operated manually. When cutting with a power saw it is deemed unsafeto secure the trigger to hold the engine speed constant since thecutting chain may encounter obstructions in the wood or the tree maybind on the cutting bar or on the chain. In that event it is necessaryto remove the cutting bar of the saw from the kerf which requires thatthe engine turn at idle speed so that the automatic clutch in thetransmission may uncouple the engine from the chain sprocket shaft andallow the chain to stop. In felling timber, because power saws representa substantial investment, after the tree begins to fall the fellerusually pulls the saw from the kerf and carries it to a position ofsafety with him, rather than leave the saw in the kerf where it may bedamaged by the falling tree. When pulling the cutting bar of the sawfrom the kerf it is necessary that the chain be stopped on the bar and alock which secures the trigger in wide open throttle position andprevents manipulation of the trigger to slow down the engine presents apossible risk of harm if it is employed by the operator. Also in fellingtimber with a power saw, under the modern practice techniques have beendeveloped to permit felling of trees having a diameter approximatelydouble the length of the cutting bar on the saw. The operator makes cutsyon each side of the tree to the depth permitted by the length of thebar and this operation requires a great deal of experience and care.Itis considered extremely unsafe to make such cuts except with a sawwith a trigger which is manually operated so as to provide the operatorwith close.

control over the cutting operation. Locking the trigger of a sawemployed in this type of cutting would be considered a very unsafepractice.

The present invention, in this preferred embodiment, provides amechanism which, although provided in the handle of an engine which maybe part of a power saw, requires the operator lto follow a prescribedsequence of operations in order to set the mechanism. It requires adeliberate act of the operator to set the mechanism and thus a safetyfeature is incorporated. With such a mechanism in the handle andavailable to be used it is deemed essential that the device be soconstructed that it cannot be accidentally placed in 'operation to lockthe trigger. Upon reference to Fig. 4 it will be observed that after thetrigger is squeezed it is impossible to push the button forward in theslot and thus it is impossible to position the hook in front of thecross pin unless the trigger is rst released. With the trigger loweredthe depending portion carried by the button inside the handle isarranged to clear the cross pin. Thus in operation of a power sawequipped with this throttle lock mechanism the operator cannotaccidentally lock the trigger and thus involve himself in diicultiessuch as have been enumerated above, whereas, if the engine is providedwith a machine attachment such as a generator or pump, the operator mayeasily set the mechanism to lock the throttle thus enabling him to leavethe machine and its engine unattended for extended periods of time.

Other objects and features of the invention will be apparent to a personskilled in the art and the scope and l-imits of the invention shall beas dened in the appended claims.

We claim:

l. In an improved handle structure for an internal combustion engine, ahollow handle, a throttle trigger pivotally mounted in the handle andadapted to be raised and lowered, a pin xed in the trigger, a slot abovethe trigger in the top of the handle extending longitudinally of saidhandle, a throttle lock button held in the slot and movable forward andback between the extremities of said slot, a latch carried below thelock button inside the handle, the latch being arranged to clear saidpin with the trigger lowered and to engage said pin with the triggerraised, and a spring mounted within said handle for biasing said buttontoward the back of said slot.

2. In an improved handle structure for an internal combustion engine, ahollow handle, a throttle trigger pivotally mounted in the handle andadapted to be raised and lowered, a pin fixed in the trigger, a slotabove the trigger in the top of the handle extending longitudinally ofsaid handle, a throttle lock button held in the slot and movable forwardand back between the extremities of said slot, a latch carried below thelock button inside the handle, the latch being arranged to clear saidpin with the trigger lowered and to engage said pin when with thetrigger raised the button is allowed to move from the forward extremitytoward the back of the slot, and a spring mounted within said handle forbiasing said button toward the back of the slot.

3. In an improved handle structure for an internal combustion engine, ahollow handle, a throttle trigger pivotally mounted in the handle andadapted to be raised and lowered, a. pin xed in the trigger, a slotabove the trigger in the top of the handle extending longitudinally ofsaid handle, a throttle locl; button held in the slot and movableforward and back between the extremities of said slot, a latch carriedbelow the lock button inside the handle, including a depending portionformed with a notch, the latch being arranged to clear said pin with thetrigger lowered and to engage said pin in the notch when with thetrigger raised the button is allowed to move from the forward extremitytoward the back of the slot, and a spring means for biasing said buttontoward the back of the slot.

4. In an improved handle structure for an internal combustion engine, ahollow handle, a throttle trigger pivotally mounted in the handleprojecting through the wall of said handle, and adapted to be moved intoand out of the handle, a slot in the handle, a throttle lock button heldin the slot and movable forward and back between the extremities of saidslot, a latch carried by the lock button inside the handle, the latchbeing arranged to clear said pin with the trigger held out of the handleand to engage said pin when with the trigger held in the handle thebutton is allowed to move from the forward extremity toward the back ofthe slot, and means biasing the button toward the back of the slot.

5. In an improved handle structure for an internal combustion engine, ahollow handle, a throttle trigger pivotally mounted in the handlealigned with the long axis of the handle and adapted to be raised andlowered, said trigger having channel sides carried vertically in thehandle, a pin fixed between the sides of said trigger, a slot locatedabove the pin in the top of the handle extending longitudinally of saidhandle, a throttle lock button held in the slot and movable forward andback between the extremities of said slot, a latch carried below thebutton inside the handle and having a depending portion held between thesides of said trigger below the pin with the trigger raised, a notchformed in the back of the depending portion, the latch being arranged toclear said pin with the trigger lowered and to engage said pin in thenotch when with the trigger raised the button is allowed to move fromthe forward extremity toward the back of the slot, and a spring meanswithin said handle for biasing said button toward the back of the slot.

6. In an improved handle structure for an internal combustion engine, ahandle having a hollow portion, a throttle trigger pivotally carried bysaid handle for pivotal movement between a raised and a loweredposition, a slot in said handle, a throttle lock button held in saidslot and movable between first and second positions adjacent oppositeends of said slot, and a latch carried by said lock button inside thehollow portion of said handle and engageable with said trigger to holdthe same in raised position only when said button is moved along saidslot from said first position into said second position while saidtrigger is held in raised position.

7. In an improved handle structure for an internal combustion engine, ahandle having a hollow portion and being provided with a slot in thehandle wall adjacent said hollow portion, .a throttle trigger pivotallycarried by said handle for pivotal movement between a raised and alowered position, a throttle lock button held in said slot and slidablealong the length of the slot between irst and second positions adjacentopposite ends thereof, a latch carried by said lock button inside thehollow portion of said handle and engageable with said trigger to holdthe same in raised position only when said button is moved along saidslot from said rst position into said second position while said triggeris held in raised position, and spring means mounted within said handlefor nrgng said throttle lock button along said slot from said firstposition into said second position.

References Cited in the tile of this patent UNITED STATES PATENTS

